Comparison of Corrosion Behavior of Zinc-Based Nanocomposite Coatings Reinforced With SiC and TiO2 Particles Fabricated Through Pulse Electroplating Process

In this research, pure zinc, Zn-SiC and Zn-TiO2 nanocomposite coatings were fabricated through pulse electroplating process from a sulphate bath. While pulse electroplating, the effect of several parameters like maximum current density (ip), frequency and duty cycle were investigated. In order to characterize the obtained coatings, surface morphology of the coatings was investigated by scanning electron microscopy (SEM & FESEM), composition of the coatings by elemental energy dispersive spectroscopy (EDS) analysis, microstructure by means of X-ray (XRD) method, corrosion measurement by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS), surface topography by the use of atomic force microscopy (AFM) and also microhardness of the coatings were investigated. The highest amount of incorporated SiC nanoparticles was 8.73 Vol. % and for TiO2 nanoparticles was 7.12 Vol. %. Also, minimum corrosion current density for pure zinc coating was 7.1, for Zn-SiC nanocomposite coating was 4.49 and for Zn-TiO2 nanocomposite coating was 4.53 μA/cm2. It was observed that utilization of simultaneous of composite coating system and also pulse electroplating process leads to significant increase in corrosion resistance. XRD analysis also showed that preferred orientation for pure zinc coating is through (002) plane. By incorporation of SiC and TiO2 nanoparticles into the zinc matrix, the intensity for (002) plane decreases and (101) plane intensity increases. Average roughness for three samples of Zn, Zn-SiC and Zn-TiO2 coatings was 528.11, 627.32 and 815.41 nm respectively. The microhardness of the coatings was also improved after SiC and TiO2 incorporation.